1. Technical Field
Exemplary aspects of the present invention generally relate to a static eliminator that eliminates static electricity on a recording medium passing through a transfer region at which a toner image formed on an image bearing member is transferred onto a recording medium, and an image forming apparatus including the static eliminator.
2. Description of the Related Art
There are two types of known image forming apparatuses: one that directly transfers a toner image formed on a latent image bearing member onto a recording medium and another that transfers a toner image primarily onto an intermediate transfer device and then onto a recording medium.
In such image forming apparatuses, when the recording medium passes through a transfer nip at which an image bearing member such as the latent image bearing member and the intermediate transfer device meets and contacts a transfer device, the transfer device forms a transfer electrical field between the recording medium and the image bearing member.
Generally, a relatively large transfer bias having a polarity opposite that of a charge polarity of toner is applied to the rear surface of the recording medium to transfer the toner image from the image bearing member onto the front surface of the recording medium. Because the transfer bias applied to the rear surface of the recording medium is relatively large, the rear surface of the recording medium having passed through the transfer nip has charges having the same polarity as that of the transfer bias, that is, the opposite polarity to the charge polarity of the toner. The charges on the rear surface of the recording medium hold the toner image onto the front surface.
However, if the charges on the rear surface of the recording medium immediately after passing through the transfer nip are excessive, sudden leakage of charges on the rear surface occurs relative to protruding members and metals disposed near a sheet transport path downstream from the transfer nip but upstream from a fixing section in a transport direction of the recording medium. In this case, the toner image on the front surface of the recording medium is disturbed, hence causing image failure.
In view of the above, static eliminators have been proposed to remove static charges from the recording medium. For example, a known static eliminator includes a static eliminating plate to remove static charges from the recording medium near the end of the transfer nip. The static eliminating plate is a conductive thin planar member made of stainless steel or the like. A plurality of static eliminating needles is formed spaced apart a certain distance between each other and parallel to a width direction of the recording medium.
The static charges on the recording medium are removed by the static eliminator near the end of the transfer nip to prevent image failure attributed to conveyance of the charged recording medium bearing an unfixed toner image.
Although advantageous, when clearing paper jams or during maintenance by technicians, clothes of the technicians may get caught by the sharp tips of static eliminating needles, resulting in breakage of the static eliminating needles.
In view of the above, there is demand for a static eliminator in which the tip of static eliminating needles is prevented from getting damaged and an image forming apparatus including the static eliminator.